Method of heading hollow stay-bolts



June 5, 1928.

Filed May 15, 922

I n flentor- Patented June 5, 1928.

CHARLES GIIIBEBH. H AWLEYe OF CHICAGO, ILLINOIS.

METHOD or- READING Application filedMay. 13,,

As is well known, the stay-bolts which are used in staying the fiat surfacesoflocomotive boilers and the like are threaded into the boiler sheets and after being settherein.

must be riveted and headed OVGI' to make them both secure and steam tight. 'Inrecent years approved boiler practices "have required the tell taling offeach stay-bolt, that is, each stay-bolt is required to'contain a small central hole long enough to reach considerably beyond the water side of the boiler sheet to the end that if the: stay bolt. is fractured, notice of the fracture shall be given by the leakage of steam or water through such tell-tale hole. My invention has-to dorwith the fastening andheading'of such stay-bolts, and particularly seeks to encourage the use of so-called hollow staybolts, that is, bolts in which the tellrtale holes are formed or drilled before the staybolts are placed in the boiler sheets. This has come to be quite a common. practice but under present method'sof heading the staybo'lts, is attended by severaltrying difliculties. The chief diflicul'tygrows out ofthe fact that in riveting over or heading the tell-tale st'ay-boltthe metal; is upset to such an extent as to close the 'tell t'ale hole,. with two annoying results' First, the tell-tale. opening must later be. boredom, and, more importantly, it is practically impossible to. know or be certain that the stay-holtflendi' has been sulfi'ciently upset or expanded to tightly fit the threadsv in "the boiler sheet, so that'the'bo'lt is likely to leak'when the. boiler is put under pressure and must'be, reheaded. Other diificulties are recognized,

but these will serveto accentuate the importance of the simple invention herein pre-' sented.

The particular'object of. my invention is to lessen the time required to headsta-ybolts, and especially to so improve. upont-he, present'methods asto insure the tightness of: every headed stay-bolt; and further to provide a. heading tool especially adapted for use with hollow stay-bolts and which shall serve to keep the tell-tale hole open during the heading operation as' contrasted withthe usual closingofthe tell-tale hole; Other objects of my invention wilt appear hereinafter. 1 My invention-"will .be readily understood on reference to the; accompanying drawings, wherein I have depicted my novel HonLow STAY-BOLTS.-

1922. Serial, No. 560,666.

stay-bolt. heading tool, die or bitt and the. method of using the same. Fig. 1 of the drawings is a side elevation of my novel heading bitt, the die end thereof beingshown in section -Fig. 2 is a section View of a portion of a boiler plate and a stay-bolt screwed into, the same ready to be headed; Fig. 3illustrates the die in operation; Fig 4 is a separate view showing the boiler sheet with the headed stay-bolt therein; Fig. 5 is an end View of'the die or bitt; Figs. 6 and 7 illustrates two modified forms of thi'sfnovettool.

It will beunderstood' that the heading tool herein shown is a die stock or bitt 'de signed for use in. a pneumatic hammer by which a great number of blows per minute may be struck. 'In Fig. 1, 2 represents the shank of the bitt and. 3 the head thereofl The'end t constit'utesthe' die surface. I This iscircular and isslightlydished or cut the dish generally conforming to a segment of asphere' of from three to 'four inches in diameter, depending on the size of the staybolt to be dealt with. The centerof the head 3 isbored out to receive the smaller pin- 5, the: lower end of which. is pointed and, will be further-described. The shank '2 has a central bore (ifthroughwhich a rod may bein'sertedi to dislodge the pin 5 from. the head. 3*, when; necessary.

The die face 4L-is hardene'd to withstand the 9 batteringwhich itreceives" from the resisting heads of the stay bolts. Thecenterpoint 5" is usually made of softer and toughermat'erial to ofiset, as-far as possible, the crystalli-zing effect of the repeated blows: Which thelight' point receives in use. Except'for this, the l'ongrpoint 5 may be made integral 'wit-h'the head of the die. However, Imuclr prefer toform the pins separatelygas'they are bound to break more frequentl than do the heads or. shanks of" these itts. Itis convenient to be able to renew the die points;

Acommonstay' bolt 7 is shown. Thisis' threadedin the opening'8 in the boiler plate 9. The outer end of the stay-bolt projects from'j i th to ths of an inch, beyond the plateaccording to the size of head required on the stay bolt. A th. inch projection is here shown and the tool shown lS'jOf the size" required in heading stay-bolts, of one inch diameter.

The stay-bolt cont-ainsa tell-tale hole, 10,

the diameter of which varies; from f ths to that is, one in which the sides are inwardly curved or dished, as clearly shown at 5 in Figs. 1, 3 and 7. Fig. 6 illustrates a true cone shape. The base of the point gradually enlarges and terminates in a flaring portion 5, which merges with the die surface 4 and the perimeter of the pin 5.

The method of using and heading the stay-bolt may be described as follows, it being understod that the die is in place in a pneumatic hammer in the hands of an operator: A stay-bolt being in the condition de picted in Fig. 2, the die is set upon the end thereof with the pin in the stay-bolt hole. Obviously the pin cannot far enter the hole. When the hammer is started into action therefore the pin is driven into the end of the tell-tale hole 10 of the stay-bolt. Meantime, the hammer is oscillated slightly to keep the pin free so that it shall not freeze in the bolt. The first effect is to so far expand the end of the stay-bolt as to forcibly set its threads into the threads in the boiler sheet 9. Having reached that condition, the resistance of the sheet to further expansion is such that from that moment forward the action of the hammer is to displace the metal of the stay-bolt outwardly, as here shown upwardly. Comparison of Figs. 2 and 3 discloses that the thickness of the finished head is greater than the initial high part or projection of the stay-bolt shown in Fig. 2. This thickening of the head is brought about by the internal and outward displacement of metal thus described. After an instants work upon the center of the stay-bolt the operator increases the oscillating or rotating action of the free end of the hammer and thus rolls the bitt around the head as depicted in Fig. 3. This action serves two purposes; it flares or increases the size of the outer end 10' of the tell-tale hole, thus doing away with the necessity of later counter-sinking the hole, and, second, the rolling action serves to force the lip 12 of the riveted head into close contact with the surface of the boiler sheet 9. Meantime, the rapidly vibrating pin has served to keep the tell-tale hole open. center pin of the die has served to keep the die in central position on the head. Furthermore, during the oscillating or rotating action of the pneumatic hammer, as will be obvious, the center pin will deliver circumferentially progressive hammer blows against the walls of the tell-tale hole, such Obviously, also, the

blows being necessarily delivered at an angle to the axis and, b reason of the fact that the pin extends wlthin the hole, such blows are delivered below the surface of the plate and simultaneously upon a radially adj acent larger part of the end of the bolt, as will be clearly apparent from Fig. 3. As the operator increases the oscillations of the hammer, the increased angle of the hammer to the axis of the stay bolt will cause the blows to be progressively applied in an outward direction with respect to the bolt, whereby the metal of the bolt is not only forced upward and outward, but the applied pressure due to the hammering action from Within the bolt, outward, expands the metal in a direction to set the full length of the threads between the bolt and the plate.

When finished, the stay-bolt has much the appearance shown in Fig. 4:. The end of the bolt is very slightly expanded and it will be found that its threads are set firmly into the threads of the boiler sheet from inside to outside, virtually precluding the possibility,

of internal corrosion- The shape of the finished head may be varied considerably by making very slight changes in the contour of the die surface. For some uses I prefer a die such as shown in Fig. 6, the a flat annular surface 13: ad aCent the en of the center pin. I Such a same presentin considerably larger than the size of'the center pin of the die- So far as keeping the tell-tale hole open is concerned, the secret appears to lie in the length of the center pin, which is substantially equal to and usually slightly ex ceeds twice the diameter of the tell-tale hole to be operated in; and in the ball shaped end of the pin, which avoids the abrasion of the lionper walls of the tell-tale hole in the stay- Because of the peculiar extruding of the metal by this tool and because of the positive expansion of the stay-bolt end so that it certainlyfills the hole in the boiler sheet, I have given to the stay-bolt heads thus formed the name extruded heads, a term best calculated to distinguish them from the ordinary stay-bolt heads. As proven by the displacement or extrusion of the stay-bolt, it is entirely improper to refer to them as expanded heads. The center expanding of stay-bolts has been attempted in the past, but in every case has proven objectionable because of the enlarging or expansionof the boiler plate and the tendency to crack or check the boiler plate. This is whollyavoided by my invention, wherein the boiler plate is not disturbed, its holding power being always greater than the resisting power of the staybolt metal in the small section or portion whereon the tool acts at any given instant. My preferred form of stay bolt heading tool is not claimed herein as the same forms the subject of a divisional application filed March 28, 1928, Serial #265,466.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. The method of tightening and heading a threaded stay bolt which has a central telltale hole and has been screwed into a correspondingly threaded hole in the plate to be stayed and left with its 'endexposed upon the outer side of said plate, that consists in delivering circumferentially progressive hammer blows against the walls of the tell-tale hole at an angle to the axis thereof and below the surface of said plate and simultaneously on a radially adjacent larger part of the end of the bolt, and during the circumferential progress of such blows progressively increasing the hammer angles with respect to the projected axis of the bolt, by such blows at the end of the bolt, increasing the length of the bolt toward the source of the blows, tightening the threads and forming a spreading head of greater height than the originally exposed end of the bolt.

2. The method of tightening and heading a threaded stay bolt which has a central tell-tale hole and has been screwed into a correspondingly threaded hole in the plate to be stayed and left with its end exposed upon the outer side of said plate, that consists in delivering circumferentially progressive hammer blows against the walls of the tell-tale hole at an angle to the axis thereof and below the surface of said plate and simultaneously on a. radially adjacent larger part of the end of the bolt, and durmg the circumferential progress of such blows progressively increasing the hammer angles with respect to the projected axis of a the bolt causing the metal of the wall of the tell-tale opening below the surface of the plate to be extruded outwardly to enlarge the head and at the same time causing the metal of the bolt to be forced towards the screw threads to tighten the same; by such blows at the end of the bolt, increasin the length of the bolt toward the source 0 the blows, and forming 'a spreading head of greater height than the originally exposed end of the bolt, and finally so increasing the hammer angle as to circularly trim the edge of the head against the plate.

In testimony whereof, I have hereunto set my hand this 6th day of May, 1922.

CHARLES GILBERT HAWLEY. 

